If you need to preface a statement like that, reword it so you're being polite. The bit in question just as easily could have said "Hey, Thanks for releasing this! Do you know when the source code will be available? Thanks for all you're hard work"
If you are releasing work on a (A/L)GPL project you started, but others contributed to without giving you other rights, you can't distribute their contributions without releasing the source.
Not trying to excuse this demand, just pointing out the technicalities. The most important point in my eyes is that with no evidence of intent to keep the source concealed for a significant amount of time, the idea that anyone would pursue a complaint under the GPL in this situation is nonsense.
It should have been "When will a source release for this be available", but the user decided to be an asshole instead and make a demand by invoking the license—even if this was required, it was stupid in context.
I think we can agree that it would not at all be weird to expect that GPL-licensed project would provide the source. Any project with multiple contributors may be legally compelled to do so. Simply asking for it is probably not being a complete ass, even if the author was wrong about the legal ramifications.
At most it could perhaps be "annoying" or a "slight ass". Being a "complete ass" would perhaps be insisting after an initial request was rebuffed or whatever.
Each releases of the software can have different licenses. This means that if the author released a new version of the software binary without the source code nor any copyright notices (like Gorden did) it is not yet released under LGPL. So nobody need to comply LGPL until he releases the source code with the license.
Even if the binary is released under LGPL without the source code, although it is odd, people still can comply the License because it is LGPL - people just need to provide a way how to link the new binary.
I don't know how quickly Gordon put up the deb file he mentioned, but just going on Pi's release I'd call it very quickly. A week or two later is more suited to an enquiry of "Glad to see pi 4 support so fast, any idea when you might get chance to put up source code?" than "hey you're REQUIRED man, get on with it already...". Better still quietly not enquiring already but just quietly checking github over the coming weeks.
Overall, it's still phrased in a demanding way.